In the early days of anaesthesia, the fasting period for liquids was kept short. By the mid-20th century \'nil by mouth after midnight\' had become routine as the principles of the management of \'full stomach\' emergencies were extended to include elective healthy patients. Back then, no distinction was made between the withholding of liquids and solids. Towards the end of the last century, recommendations of professional anaesthesiology bodies began to reduce the fasting time of clear liquids to 2 h. This reduction in fasting time was based on the understanding that gastric emptying of clear liquids is rapid, exponential, and proportional to the current filling state of the stomach. Furthermore, there was no evidence of a link between drinking clear liquids and the risk of aspiration. Indeed, most instances of aspiration are caused by failure to identify aspiration risk factors and adjust the anaesthetic technique accordingly. In contrast, long periods of liquid withdrawal cause discomfort and may also lead to serious postoperative complications. Despite this, more than two decades after the introduction of the 2 h limit, patients still fast for a median of up to 12 h before anaesthesia, mainly because of organisational issues. Therefore, some hospitals have decided to allow patients to drink clear liquids within 2 h of induction of anaesthesia. Well-designed clinical trials should investigate whether these concepts are safe in patients scheduled for anaesthesia or procedural sedation, focusing on both aspiration risk and complications of prolonged fasting.

BACKGROUND: Preoperative anesthesia long time fasting, may increase patient hemodynamic instability during surgery and may affect the patient\'s post-surgery electrolyte balance. No meta-analysis has been conducted to explore the effects of preoperative liquid intake amount on gastric fluid PH, gastric fluid volume, surgery inhalation of pulmonary complications, and patient self-perceptions quality of care systematic review and meta-analysis of the literature.
OBJECTIVE: To assess the pros and cons of preoperative liquid intake using a systematic review of the literature.
METHODS: The authors searched ten databases including NRC (Nursing Reference Center), CINAHL (Cumulative Index to Nursing and Allied Health Literature), WOS (Web of Science), PubMed, The Cochrane Library, UpToDate, DynaMed, NGC (National Guideline Clearinghouse), Airiti Library, and National Digital Library of Theses and Dissertations in Taiwan, to identify relevant articles that were published from 2003 to January 2017. Nine qualified articles were included in the analysis from the 30 articles that were selected using an initial keyword search. The Oxford Centre for Evidence-based Medicine 2011 Levels of Evidence was used as the evidence grade and the CASP (Critical Appraisal Skills Program) was used to evaluate the quality of the selected articles. The quantitative results were analyzed using Review Manager, Version 5.1.
RESULTS: The quality of the literature was medium to high. A small to moderate dose of fluid consumed at 2 hours prior to surgery did not significantly increase gastric fluid volume during anesthesia, with a combined effect of 2.37 (95% CI [-5.12, 9.85], p = .54), and had no effect on gastric fluid PH, with a combined effect of 0.10 (95% CI [0.00, 0.20], p = .05).
CONCLUSIONS: The results indicate that consuming a small to moderate dose of liquid at 2 hours prior to the provision of anesthesia does not significantly increase the gastric fluid volume or gastric fluid PH of patients during anesthesia. Moreover, the positive benefits of consuming this dose of liquid include reduced risks of aspiration pneumonia, gastroesophageal reflux disease, and postoperative complications as well as reduced perceptions of thirst and hunger during the immediate preoperative period. Thus, this analysis supports that the advantages of allowing patients to consume a moderate or smaller dose of liquid prior to surgery outweigh the disadvantages.
BACKGROUND: 術前進食液體利弊之系統性文獻探討暨統合分析.
UNASSIGNED: 術前長時間禁食，可能會增加手術期間血液動力學不穩定，甚至影響術後電解質平衡。目前國內缺乏探討禁食時間、進食的液體量對於胃液酸鹼值、胃殘餘量、手術中吸入性肺併發症及病人自覺感受之系統性文獻回顧。.
UNASSIGNED: 以系統性文獻回顧及統合分析，探討術前進食液體之利弊。.
UNASSIGNED: 以中英文關鍵字及設定條件，搜尋NRC（Nursing Reference Center）、CINAHL（Cumulative Index to Nursing and Allied Health Literature）、WOS（Web of Science）、PubMed、The Cochrane Library、UpToDate、DynaMed、NGC（National Guideline Clearinghouse）、華藝線上圖書館及臺灣碩博士論文知識加值系統，共十個資料庫，時間設定2003年至2017年1月，共獲得30篇文獻，排除不符合條件之文獻後共9篇納入分析。依據「牛津大學實證醫學證據等級表2011版」來進行證據等級評定，文章品質則運用CASP（Critical Appraisal Skills Program）作為評讀工具，以RevMan 5.1版進行統合分析。.
UNASSIGNED: 文獻品質介於中等至高等，術前2小時進食少量至中量的液體，並未顯著增加病人麻醉期間的胃殘餘量，其效果量為2.37（95% CI [-5.12, 9.85], p = .54）；亦未影響胃液酸鹼值，效果量為0.10（95% CI [0.00, 0.20], p = .05）。.
UNASSIGNED: 結果顯示，術前2小時進食少量至中量液體，並未顯著增加病人麻醉期間之胃殘餘量及胃液酸鹼值，此外其益處可降低手術中吸入性肺炎、胃食道逆流及併發症發生的風險，更能減緩術前口渴與飢餓感受，此分析進而支持手術前進食少量至中量液體，顯示其優點多於弊。.